Answer
Factor : $x^{2}$ + 12x + 20
To begin by writing the first terms of the binomial factors
(x + $\triangle$)(x + $\square$)
Next, to look for two numbers whose product is +20 and whose sum is +12. As the two numbers must have a positive product and a positive sum, pairs of positive factors of 20 are to be investigated only.
Factors of 20 $\Longleftrightarrow$ Sum of Factors
1,20 $\Longleftrightarrow$ 21
2,10 $\Longleftrightarrow$ 12 (Correct sum)
4,5 $\Longleftrightarrow$ 9
Thus, $x^{2}$ + 12x + 20 = (x + 2)(x + 10)
Work Step by Step
Factor : $x^{2}$ + 12x + 20
To begin by writing the first terms of the binomial factors
(x + $\triangle$)(x + $\square$)
Next, to look for two numbers whose product is +20 and whose sum is +12. As the two numbers must have a positive product and a positive sum, pairs of positive factors of 20 are to be investigated only.
Factors of 20 $\Longleftrightarrow$ Sum of Factors
1,20 $\Longleftrightarrow$ 21
2,10 $\Longleftrightarrow$ 12 (Correct sum)
4,5 $\Longleftrightarrow$ 9
Thus, $x^{2}$ + 12x + 20 = (x + 2)(x + 10)
